Let us elaborate you in what circumstances you can increase document rendering performance. API performance depends on content of the documents. Documents differ with each other with respect to the content they posses like there can be tables/charts/images etc.

So, viewer may take some time to render a document for the first time. However, if you enable cache true as follows:

config.setUseCache(true);

You can see change in the response time of any large document’s rendering process. Attached is the snapshot of rendering html output and time comparison.

Yes, that’s the purpose of cache system. So that viewer must not consume a lot of time in rendering a new large file every time. Once a file/document is cached, it’d be read/rendered from cache, that saves time.

Consider a large document with 1000+ pages. Rendering it every time by disabling cache will consume a lot of time and system resources, eventually it will effect viewer’s performance (time based). Hence, we’d recommend you to keep cache enabled.